MTN Cancellation Department forever unreachable but quick to take calls for new sales!!!!!

MTN called me about my number being due for an Upgrade this month and when i told them i dont want to upgrade anymore but to just end my contract during the call the consultant said its not a problem he can do that but he never assisted nor ever called back, and for the previous days we call the cancellation department and there is never any answer you spent hours and hours on the line. What else is there to do because we dont want to continue with the contract as we have never missed a payment and we have paid to the end. Service Delivery from MTN is quick to take sales but unable to see it through post taking their contract.